Much of the research in the field of fiber-optic sensors dates back more than 30 years. In that time, numerous types of fiber-optic sensor technologies were developed. Fiber-optic sensors have been designed to sense various parameters of light. These include intensity changes, polarization states, and wavelength shifts. Their popularity is due to their numerous potential benefits. These benefits include EMI immunity, remote interrogation capabilities, and the ability to multiplex hundreds of sensors in both time and wavelength on a single fiber. One of the most popular fiber-optic technologies is in the field of interferometers.
Fiber-optic interferometers provide the highest sensitivity and widest dynamic range of any available fiber-optic sensor technology. They are also capable of remote interrogation and can be multiplexed into large-channel-count arrays. Because of these characteristics, fiber-optic interferometers are generally well suited for applications such as large acoustic and vibration sensing arrays. However, for some applications, even the wide dynamic range of the interferometer is still insufficient.
The wide dynamic range of fiber-optic sensors, however, is still insufficient in a number of highly desirable applications. This is partially evident by the number and type of fiber-optic sensor systems currently deployed in real-world applications. Despite the fact that the majority of the research in the field was conducted in the 1980's and 1990's, only a few select fiber-optic sensor systems have reached production stage. These systems all have modest dynamic range requirements. There are currently no large-scale fiber-optic interferometric sensor systems in use by the research and development community, despite their significant benefits.